Oxynitrate additive for polyurethane foams

ABSTRACT

In a process for producing polyurethane foam by allowing a reaction mixture comprising at least one polyisocyanate component and at least one polyfunctional active hydrogen component to react, a compound selected from the group consisting of oxynitrate salts of metals of Group IV B of the Mendeleef periodic table, is employed as a cell opening additive. Such oxynitrate salts are also effective to modify tin tolerance of urethane formulations. The oxynitrate compounds are effective in both free rise and molded foam processes. Cell opening is accomplished, for instance, by reacting toluene diisocyanate with a polypropoxy/polyethoxy polyol in the presence of an oxynitrate salt of a Group IV B metal, such as zirconium oxynitrate, to form a foam having more open cells than a similar foam without oxynitrate.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation, of application Ser. No. 224,519, filed July 25,1988.

This invention generally concerns the field of polyurethane foams. Morespecifically, it concerns formation of open cell polyurethane foams.

Formation of a foamed or cellular polyurethane involves generation,volatilization or expansion of a gas or vapor during polymerization of areaction mixture of polyurethane-forming components while the reactionmixture is in a liquid or plastic state. As the gas or vapor expands,bubbles are formed in the reaction mixture. The bubbles expand, formingcells of approximately spherical shape in the reaction mixture. As morecells form and cells expand, they contact one another and, when optimumpacking structure is achieved, take generally polygonal shapes havinggenerally polygonal sides or faces in common with adjacent cells.Membranes of polyurethane are formed at the faces. At intersections ofthe faces there are heavier strands of material. When the polyurethanesolidifies, these strands provide a skeletal framework for the foam.Although there are cells of varying geometry in an actual foam, ageneral structure having heavier skeletal strands and thinner membranousfaces is obtained.

An open cell foam is a foam in which sufficient membranes are absent orbroken from the faces of the cells that there is communication betweencells. A free rise foam, e.g. slab foam, is generally considered opencell when there is little or no resistance to the forced passage of air.Free rise foams having air flow measurements of less than 0.1 cubic feetper minute are referred to as closed cell foams.

In the case of molded foams, closed cell foams generally shrink markedlyafter foaming because gas trapped in the foam cells contracts withcooling, lowering the pressure in the cells such that they cannotwithstand atmospheric pressure. Open cell foams shrink less than closedcell foams because communication between cells allows equalization ofpressure inside and outside each cell. Lack of substantial shrinkagegenerally indicates presence of open cells. Ingredients of a formulationfor forming a molded foam are carefully balanced to achieve a foam whichneither shrinks substantially nor collapses. When there are insufficientopen cells in a foam, crushing of the foam, e.g. by passing it betweenrollers, is often necessary.

Open cell foams are porous and are useful as filters, gas-liquidcontacting devices, catalyst carriers, rug pads, door mats, sponges,insulating pads, spacing devices, mattresses, flexible partitions,baffles, diffusers, draperies, upholstering padding, pillows, liningsfor fabrics, acoustic insulation and the like.

Open cell foams are often formed by reticulation, that is, by formationof a generally closed cell foam and removal of the membrane faces of thecells. Oxidation, hydrolysis, explosions, enzymes and the like have beenused for reticulation.

Cell opening can also be achieved by adding certain compounds referredto as cell opening additives to formulations suitable for formingpolyurethane foams. Several types of cell opening additives have beenused to cause rupture of the membranes and cell opening during formationof a foam. Cell opening additives include siloxane-oxyalkylene blockcopolymers, mixtures of acetone and cyclopentane, alkyl and alkenylesters. Such cell opening additives often interfere with some reactionsin a formulation or otherwise affect the physical properties of a foam.Such additives have not achieved wide acceptance because they are oftenformulation specific, and resulting foams often exhibit cross-sectionalnon-uniformity in air flow.

Polyurethane foams are frequently sensitive to the amount oftin-containing catalyst used in preparation of the foam. An increase inthe amount of tin-containing catalyst outide of a limited range for eachfoam formulation generally produces shrinkage of the foam. Use of lesstin-containing catalyst than indicated by the range generally produces asplit and friable foam. The range of amounts of tin-containing compoundsthat can be used without causing shrinkage or splitting sufficient tomake the foam less useful for its intended purpose is referred to hereinas tin tolerance. Tin tolerance varies widely with particularformulations used for foaming. Modification of tin tolerance facilitatesthe formulation of foams having desired physical properties.

SUMMARY OF THE INVENTION

In one aspect, the invention is a process for producing polyurethanefoam by allowing a reaction mixture comprising at least onepolyisocyanate component and at least one polyfunctional active hydrogencomponent to polymerize, the improvement which comprises employing as anadditive, a compound selected from the group consisting of oxynitratesalts of metals of Group IV B of the Mendeleef periodic table.

In another aspect, the invention is a composition comprising a polyetherpolyol and at least one oxynitrate salt of a metal of Group IV B of theMendeleef periodic table.

The oxynitrate additives used in the process of the invention areeffective and widely applicable cell opening additives useful in avariety of polyurethane foam formulations and processes without causingsignificant deterioration of physical properties of foams formed. Cellopening is observed when the additives of the invention are used inpolyurethane formulations suitable for forming slab stock foams ormolded foams. The oxynitrate additives also generally modify the tintolerance of a foam formulation. Generally, it is possible to use moretin-containing catalyst in a formulation having therein an oxynitratesalt than would be possible in the absence of the oxynitrate withoutsubstantial shrinkage.

DETAILED DESCRIPTION OF THE INVENTION

Oxynitrate additives used in the practice of the invention are compoundsselected from the group consisting of oxynitrates of metals of Group IVB of the Mendeleef periodic table. Such compounds include zirconium,hafnium, and titanium oxynitrates. The oxynitrates are preferably usedin the form of hydrated salts, more preferably where an average of atleast about 2 water molecules is associated with each metal oxynitratemolecule. Zirconium oxynitrate, also known as zirconyl nitrate,ZrO(NO₃)₂ ·X H₂ O is preferred for use as a oxynitrate additive of theinvention for reasons of safety, convenience, solubility andeffectiveness. X is preferably from about 2 to about 6, more preferablyfrom about 5 to about 6. Oxynitrates are commercially available in theform of powder or a solution in water.

The oxynitrate additives are conveniently used in the form of solutionsor dispersions. It is believed that solutions of the additives are moreuseful as cell openers than are dispersions thereof. It is, however,noted that concentrations of the oxynitrate additives in liquidstypically decrease on filtration and that concentration decreases morewith filtration through a finer filter than with filtration through acoarser filter. Such a phenomenon indicates a possibility of dispersionsof very small particles of oxynitrate additives rather than, or inaddition to, true solutions. The particles would be small enough to passthrough the filters used in the practice of the invention. The term"solution" is used herein to refer to mixtures of oxynitrate additivesand liquids suitable for use in the practice of the invention, eventhough a fine dispersion may be present.

When solutions of the oxynitrate additives are used in the practice ofthe invention, they are suitably prepared in water or in other liquidsin which the oxynitrate additive is at least partially or slightlysoluble. It is advantageous to utilize a component of a polyurethaneformulation as solvent or carrier for the oxynitrate additive. Use of aformulation component avoids dilution of a formulation with materialswhich could have undesirable effects on the polyurethane foam producedfrom the formulation. Water or another active hydrogen component of apolyurethane formulation, which component is inert to the oxynitratesalt used, is conveniently used as solvent for oxynitrate additives usedin the practice of the invention. A component is inert to an oxynitratesalt if it does not react or otherwise interact with the oxynitrate suchas to make it substantially less effective. A reduction in effectivenesswhich can be compensated for by increased concentration of oxinitrate ina formulation is not generally considered substantial in the practice ofthe invention.

Liquids advantageous for dissolving or dispersing the oxynitrateadditives used in the practice of the invention include active hydrogencompounds such as water and polyols. Polyols in which the oxynitrateadditive forms solutions having concentrations greater than about 3 ppmby weight are the preferred polyols. The polyols are suitably any polyolsuitable for use as a polyfunctional active hydrogen component inproducing a polyurethane foam. Polyether polyols are preferred and,advantageously, are produced from alkylene oxides including ethyleneoxide, propylene oxide, butylene oxide and the like. The oxynitrateadditives are typically more soluble in polyether polyols havingrelative higher molecular weights and/or relatively higher proportionsof ethylene oxide. Formulations such as formulations for producing slabfoams employ polyols having average molecular weights of from about 1500to 6000, preferably from about 3000 to about 4000, as a major portion ofthe active hydrogen components; in such formulations, the oxynitrateadditives used in the practice of the invention are preferably dissolvedor dispersed in the polyol rather than water. In such formulationssuitable for forming free rise foams, water solutions of the oxynitrateadditives are generally less effective. In formulations suitable forforming molded foams, water is a preferred solvent for the oxynitrateadditives used in the practice of the invention. Such formulationstypically have as a major active hydrogen component a polyol which hasan average molecular weight of about 1000 to about 6000, preferably fromabout 3500 to about 5000.

Solutions of the oxynitrate additives in liquids suitably haveconcentrations of the additives ranging from barely detectable amountsup to about saturation concentrations. Supersaturated solutions are alsosuitably used. When the oxynitrate additive is only slightly soluble ina liquid, use of nearly saturated solutions of oxynitrate additives inthe liquid is often convenient to avoid addition of more liquid than issuitable for use in the polyurethane formulation. Oxynitrate additivessuch as zirconium oxynitrate and the like preferably used in solutionshaving concentrations of at least about 3 parts per million (ppm)(anhydrous) oxynitrate salt in a liquid. More preferably, the oxynitrateadditives are used in solutions of from about 3 ppm to about 10 weightpercent in a liquid. Most preferably, concentrations of the additives inwater range from about 0.025 to about 10 percent by weight; whileconcentrations in organic liquids most preferably range from about 5 toabout 50 ppm by weight.

For instance, typical concentrations of zirconium oxynitrate hexahydratein water are generally less than about 10 percent by weight andconveniently range from about 0.5 to about 5 percent by weight based onweight of the aqueous solution. Preferably, concentrations of from about1 percent to about 2 weight percent are used. While zirconium oxynitrateis conveniently dispersed and dissolved in typical polyols, such asthose which are block or random copolymers of ethylene oxide and/orpropylene oxide, to form mixtures having concentrations less than about1500 ppm by weight, such mixtures, after filtration, leave solutionshaving concentrations in the range of about 10 ppm to about 700 ppm byweight. Generally, concentrations of (anhydrous) zirconium oxynitrate ina polyol after filtrations and suitable for use in the practice of theinvention are from about 1 to about 500 ppm, preferably from about 5 toabout 50 ppm, more preferably from about 5 to about 25 ppm by weightbased on weight of the solution.

The oxynitrate additive is suitably dissolved or dispersed directly in aliquid to be used in a polyurethane formulation. Alternatively, theadditive is first admixed with a first liquid such as tetrahydrofuran,methanol, water and the like, and the admixture thereof is subsequentlydissolved or dispersed in a second liquid suitable for use in apolyurethane formulation. The first liquid is allowed to remain in thesecond, or is, alternatively, removed. For instance, the additive mayconveniently be dissolved in a first liquid such as methanol, thendispersed in an active hydrogen component such as a polyol for use in apolyurethane formulation. Where it is desirable to remove the firstliquid from the second liquid or active hydrogen component, removal isaccomplished by means known in the art for such removal such asevaporation of the first compound, distillation, vacuum distillation,gas/vapor stripping, solvent exchange and the like.

Solutions of oxynitrate salts in liquids are suitably formed by mixingmore than the amount of oxynitrate salt required for a desiredconcentration with the liquid to form a coarse dispersion, which oftenhas visible particles of oxynitrate salt therein. Then the dispersion isfiltered. It is generally preferable to use a filter with a pore size ofless than about 60 microns, such as glass frit filter. A glass fritfilter is a filter made by sintering frit, that is, glass which has beenmelted and quenched to form small particles which are, optionally,milled. Exemplary of such filters are those commercially available fromFischer Scientific Company under the designation glass frit filterfunnels. Glass frit filters designated as fine, medium or coarse, thatis filters having openings of a size ranging from about 4 microns toabout 60 microns in diameter are preferred for filtering solutions ofthe oxynitrate additives used in the practice of the invention. Glassfrit filters designated as fine or medium, that is filters havingopenings of about 4 microns to about 15 microns are more preferred.Filtration through commonly avilable paper filters, for instance Whatman#40 ashless filters, is usually insufficient to produce desired results.It is believed that such filtering fails to sufficiently removeparticles having sizes that can have an adverse effect on the structureof foams produced. In some instances, solutions of zirconyl nitrate inpolyols which are filtered through paper filters can cause foams tocollapse. Preferably, particles present in a solution of zirconiumoxynitrate are less than about 60 micros in diameter.

A mixture of liquid and oxynitrate salt is suitably heated to achievesolution of the salt in the liquid. Heat sufficient to degrade the saltor liquid is generally avoided.

In using the oxynitrate additives used in the practice of the invention,contact with compounds which are highly acidic or highly basic shouldgenerally be avoided to maintain the full activity of the oxynitrateadditive. Such acidic and basic compounds include, for instance, mineralacids, and alkali metal hydroxides.

The oxynitrate additives used in the practice of the invention are usedin an amount sufficient to produce a foam having measurably more opencells than a foam produced from the same components, and under the sameconditions, but without the oxynitrate additive. In the case of freerise foams, open cells are typically indicated by air flow measurementsby the procedure of ASTM D-3574-86 (Test G). Open cells can also bedemonstrated by microscopy. In the case of molded foams, lack ofsubstantial shrinkage is indicative of open cells. An extent of cellopening is generally preselected between that which would result insubstantial shrinkage and that which would result in collapse. Withinthat range, an extent of cell opening is preselected based on propertiesneeded in the foam. For instance, a foam to be used as a filter willhave a preselected extent of cell opening sufficient to allow fluids topass through and insufficient to allow passage of solids of preselectedsizes. Generally, the oxynitrate additives used in the practice of theinvention are used in total amounts sufficient to produce a preselectedextent of cell opening.

Alternatively, the oxynitrate additives used in the practice of theinvention are used in amounts sufficient to modify tin tolerance of areaction mixture or polyurethane formulation. The tin tolerance isgenerally increased, that is, more tin may generally be used with anoxynitrate additive than may be used to produce a satisfactory foamwithout the additive. The range of tin concentrations that are suitablyused to produce a foam is also generally increased by use of anoxynitrate additive. The effect of the oxynitrate additives on tintolerance is especially notable in molded polyurethane orpolyurethane-polyurea foams.

The cell opening effect of the additives of the invention is generallyobservable when the additive is used in amounts greater than about 2parts per million by weight (ppmw) based on total active hydrogencomponents. The amount of oxynitrate additive needed in a formulationdepends on the extent of cell opening observed in using the formulationwithout the additive. In free rise polyurethanes, that is polyurethanesallowed to foam in open containers or on substrates such as on conveyorbelts, such as polyurethanes produced in processes commonly referred toslab stock processes, the oxynitrate additives of the invention arebeneficially used in amounts ranging from about 2 to about 150,preferably from about 3 to about 50, more preferably from about 3 toabout 20 ppmw based on total active hydrogen component. In polyurethanefoams molded in closed molds, the additives of the invention areadvantageously used in amounts of about 2 to about 700 ppmw, preferablyfrom about 2 to about 20, more preferably from about 3 to about 15 ppmw.

A oxynitrate additive of the invention is advantageously dissolved ordispersed in a component of a polyurethane formulation, and thatcomponent is added to, mixed with and processed with other componentsand additives in generally the same manner as those components areadded, mixed and processed in processes of forming polyurethane foamsknown to those skilled in the art. Typically, an admixture of oxynitrateadditive and an active hydrogen component or water is formed andfiltered, then mixed with other active hydrogen components and additivesthat may be used to form a mixture thereof. The mixture is then admixedwith the isocyanate component(s) to form a reaction mixture. Thereaction mixture is exposed to conditions suitable for foaming andpolymerization. Such processes as slab foam processes and molded foamprocesses and the like are suitably used. Variations in the practice ofthe invention as applied in slab foam and molded foam processes arenoted herein.

It is recognized in the art that preparation of commercially usefulfoams requires careful balancing of a large number of factors includingthe components outlined above, catalysts, surfactants, temperatures,speeds of mixing and feeding the foaming mixture to a mold and reactionconditions. The proportion of oxynitrate additive is yet another factorto be balanced in producing a commercial foam. General procedures andproblems of providing a balanced mixture and process conditions suitablefor a given apparatus are well known to those skilled in the art.

For example, proportions of polyisocyanate component to active hydrogencomponents, including water, can be varied as a means for changingproperties of the polyurethane foam including air flow. Generally therelative proportion of equivalents of polyisocyanate component toequivalents of total active hydrogen components is adjusted to provide aratio of from about 0.7 to about 1.5 equivalents of isocyanate perequivalent of active hydrogen component. Different ratios are useful toachieve different properties in foam, but generally an excess ofisocyanate component is beneficial in obtaining a fully polymerized,stable and useful foam product. The relative proportion ofpolyisocyanate components to active hydrogen components is generallyexpressed as isocyanate index. The isocyanate index is the ratio of thenumber of isocyanate groups in the polyisocyanate component to thenumber of isocyanate-reactive groups in the active hydrogen startingcomponents multipled by 100. The polyisocyanate starting component isused in a quantity which provides an isocyanate index for the reactionmixture of from about 70 to about 150, preferably from about 90 to about130, more preferably from about 100 to about 120.

The term, polyurethane, is used generically herein to denote polymersproduced by reaction of at least one polyisocyanate component and atleast one polyfunctional active hydrogen component. In the case ofmixtures, properties such as hydroxyl functionality or isocyanatefunctionality are described as an average for components in a mixture.Active hydrogen components are compounds having hydrogen-containingfunctional groups which will react with an isocyanate group. TheZerewitnoff test described by Woller in the Journal of the AmericanChemical Society, Vol. 49, page 3181 (1927) predicts the tendency of ahydrogen-containing group to react with iscyanates. Compounds havinghydroxyl functional groups are preferred active hydrogen compounds forproducing polyurethanes using the practice of the invention. Suitableactive hydrogen compounds are generally liquids or solids capable ofbeing melted at relatively low temperatures.

Polyisocyanate starting components have two or more isocyanate groups.Diisocyanates are typically used as polyisocyanate starting components.The choice of starting components, as well as the process by which theyare reacted, generally determines physical properties of a polyurethane.

Active hydrogen components most commonly used in polyurethane productionare those compounds having at least two hydroxyl groups, which compoundsare referred to as polyols. Typical polyols include polyester polyols,polyester amide polyols, and polyether polyols having at least twohydroxyl groups. Polyethers and polyesters having hydroxyl terminatedchains are preferred for use as relatively high molecular weight activehydrogen containing compounds for use in polyurethanes suitable for usein the practice of the invention. Examples of polyols also includehydroxy functional acrylic polymers, hydroxyl-containing epoxy resins,polyhydroxy terminated polyurethane polymers, polyhydroxyl-containingphosphorus compounds and alkylene oxide adducts of polyhydricthioethers, including polythioethers, acetals, including polyacetals.

Polyether polyols preferably employed in the practice of this inventionare polyalkylene polyether polyols including the polymerization productsof oxiranes or other oxygen-containing heterocyclic compounds such astetramethylene oxide in the presence of such catalysts as borontrifluoride, potassium hydroxide and the like, or initiated by water,polyhydric alcohols having from about two to about eight hydroxylgroups, amines and the like. Illustrative alcohols suitable forinitiating formation of a polyalkylene polyether include ethyleneglycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butylene glycol,1,3-butylene glycol, 1,2-butylene glycol, 1,5-pentane diol, 1,7-heptanediol, glycerol, 1,1,1-trimethylolpropane, 1,1,1-trimethylolethane,hexane-1,2,6-triol, alpha-methyl glucoside, pentaerythritol, erythritol,pentatols and hexatols. Sugars such as glucose, sucrose, fructose,maltose and the like as well as compounds derived from phenols such as(4,4'-hydroxyphenyl)2,2-propane, and the like are also suitablepolyhydric alcohols for initiating formation of polyether polyols usefulin the practice of the invention.

Amines suitable for reaction with oxiranes to form polyether polyolsinclude aromatic amines such as aniline, o-chloraniline, p-phenylenediamine, 1,5-diaminonaphthalene, methylene dianiline, the condensationproducts of aniline and formaldehyde, 2,4-diamino toluene and the like;aliphatic amines such as methylamine, triisopropanolamine,isopropanolamine, diethanolamine, ethyenediamine, 1,3-propylenediamine,1,4-propylene diamine, 1,3-butylenediamine, and the like and mixturesthereof. Amine based polyols are exemplified by those disclosed in U.S.Pat. No. 4,358,547.

Exemplary oxiranes suitable for preparation of polyether polyols includeethylene oxide, propylene oxide, butylene oxide, amylene oxide, glycidylethers such as t-butyl glycidyl ether, phenyl glycidyl ether, and thelike, as well as block or random copolymers of two or more of theseoxiranes. Polyether polyols are also prepared from starting mterialssuch as tetrahydrofuran and alkylene oxide copolymers withtetrahydrofuran; epihalohydrins such as epichlorohydrin; arylalkyleneoxides such as styrene oxide and the like. Preferably, the polyetherpolyols are prepared from alkylene oxides having from about two to aboutsix carbon atoms such as ethylene oxide, propylene oxide, and butyleneoxide. Polyether polyols suitable for use in the practice of theinvention are preferably selected from the group consisting of randomcopolymers produced from mixtures of ethylene oxide and propylene oxide,and polymers of propylene oxide at least partially capped with ethyleneoxide to provide primary hydroxyl groups. The polyether polyolspreferably have from about 2 to about 3 hydroxyl groups per molecule.The polyether polyols may be prepared by processes known to thoseskilled in the art such as those processes described in Encyclopedia ofChemical Technology, Vol. 7, pp. 257-262, Interscience Publishers(1951); M. J. Schick, Nonionic Surfactants, Marcel Dekker, New York(1967); British Pat. No. 898,306; and U.S. Pat. Nos. 1,922,459;2,871,219; 2,891,073; and 3,058,921.

Suitable hydroxyl-containing polyesters for use as relatively highequivalent weight active hydrogen compounds in the practice of theinvention include those obtained from polycarboxylic acids orpolycarboxylic acid anhydrides and polyhydric alcohols. Thepolycarboxylic acids and anhydrides are suitably aliphatic,cycloaliphatic, aromatic or heterocyclic; they are, optionally,substituted, e.g. by halogen atoms and are, optionally, unsaturated.Illustrative polycarboxylic acids include oxalic acid, malonic acid,succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid,azelaic acid, sebacic acid, oleic acid, trimellic acid, maleic acid,fumaric acid, glutaconic acid, alpha-hydro muconic acid,beta-hydromuconic acid, alpha-butyl-alpha-ethyl-glutaric acid,alpha-beta-diethylsuccinic acid, phthalic acid, isophthalic acid,terephthalic acid, hemimellitic acid, 1,4-cyclohexane-dicarboxylic acidand the like. Any suitable aromatic, aliphatic or heterocyclicpolyhydric alcohol may be used. Exemplary polyhydric alcohols includeethylene glycol, 1,2-propylene glycol, 1,2-propylene glycol,1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol,1,5-pentane diol, 1,4-pentane diol, 1,3-pentane diol, 1,6-hexane diol,1,7-heptane diol, glycerol, neopentyl glycol, 1,1,1-trimethylolethane,1,1,1-trimethylolpropane, hexane-1,2,6-triol, tetraethyleneglycol,polypropylene glycol, alpha-methyl glucoside, pentaerythritol, sorbitol,quinitol, mannitol, and the like as well as compounds derived fromphenols such as 2,2-(4,4'-hydroxyphenyl)propane,bis(4,4'-hydroxyphenyl)sulfide, bis(4,4'-hydroxyphenyl)sulfone and thelike. Polyesters of lactones such as caprolactone and the like orhydroxycarboxylic acid such as hydroxycaproic acid and the like are alsosuitable active hydrogen containing components.

Other polyols suitable for use in the practice of the invention includepolyacetones, hydroxy functional acrylic polymers such as polymers ofhydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropylacrylate, hydroxypropyl methacrylate, and the like; polymers ofethylenically unsaturated carboxylic acids such as polymers of vinylacetate like polyvinyl acetate and the like; hydroxyl-containing epoxyresins; urea-formaldehyde and melamine-formaldehyde resins;hydroxyl-containing polycarbonates, such as those prepared by thereaction of diols, such as 1,3-propanediol, 1,4-butanediol,1,6-hexanediol, diethylene glycol, triethylene glycol or tetraethyleneglycol, with diarylcarbonates, e.g. diphenylcarbonate, or phosgene;hydroxyl-containing polyurethanes; methylol resins; starches and othercellulosic polymers; condensation polymers of aniline and formaldehydeand the like; acrylamide polymers; and the like.

Low molecular weight aliphatic polyols such as 1,4-butane diol, ethyleneglycol, trimethylolpropane, diethylene glycol,1,4-cyclohexanedimethanol, and the like; aromatic ring-containing diolssuch as bis-hydroxyethylhydroquinone, bisphenols, catechol, resorcinoland the like; amide or ester containing diols and the like are suitablefor use in the practice of the invention. Mixtures of these lowmolecular weight polyols and higher molecular weight polyols aresimilarly useful.

Representatives of the suitable polyols are generally known and aredescribed in such publications as High Polymers, Vol. XVI,"Polyurethanes, Chemistry and Technology" by Saunder-Frisch,Interscience Publishers, New York, Vol. I, pp. 32-42, 44-54 (1962) andVol. II pp 5-6, 198-199 (1964); Kunststoff-Handbuch, Vol. VII,Vieweg-Hochtlen, Carl-Hanser-Verlag, Munich, pp. 45-71 (1966); andOrganic Polymer Chemistry by K. J. Saunders, Chapman and Hall, London,pp. 323-325 (1973); and Developments in Polyurethanes, Vol 1, J. M.Burst, ed., Applied Science Publishers (1978) pp. 1-76.

Polyols which contain high molecular weight addition or condensationpolymers in a finely dispersed form or in solution are optionally used.Such polyols are often called polymer polyols and are obtained whenpolymerization reactions are carried out in situ in the polyolsdescribed above. Processes for the production of these polyols aredescribed in U.S. Pat. Nos. 3,869,413; Re. 28,715; Re. 29,014; and Re.29,118, which are incorporated herein by reference. For instance,polyethers may be modified with vinyl polymers, e.g., by thepolymerization of styrene and/or acrylonitrile in the presence of thepolyethers. Polyols having dispersed polyurethane or polyurea particlesare also suitable.

Polyisocyanate starting components suitable for use in the practice ofthe invention are organic compounds that contain at least two isocyanategroups. Such compounds are well known and readily availablecommercially. Polyisocyanate starting components include aromatic,aliphatic and cycloaliphatic polyisocyanates and combinations thereof.Representative polyisocyanates include diisocyanates such as m-phenylenediisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate,hexamethylene-diisocyanate, tetramethylene-diisocyanate,cyclohexane-1,4-diisocyanate, hexahydrotoluene diisocyanate (and isomersthereof), naphthylene-1,5-diisocyanate,1-methoxyphenyl-2,4-diisocyanate, diphenylmethane-4,4'-diisocyanate,diphenylmethane-2,4'-diisocyanate, 4,4'-biphenylene diisocyanate,3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 3,3'-dimethyl-4,4'-biphenyldiisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate and thelike; triisocyanates such as 4,4',4"-triphenylmethane triisocyanate,toluene-2,4,6-triisocyanate, and the like; tetraisocyanates such as4,4'-dimethyldiphenyl-methane-2,2',5,5'-tetraisocyanate,4,4'-dicyclohexane-diisocyanate, isophorone diisocyanate, isomers ofeach and the like; as well as other polyisocyanates such aspolyphenylisocyanate and the like and mixtures thereof. Toluenediisocyanate, diphenylmethane-4,4'-diisocyanate,diphenylmethane-2,4'-diisocyanate and polymethylene polyphenylisocyanateare beneficial for use in the practice of the invention because of theiravailability and properties. Mixtures of polyisocyanate components aresuitably used in the practice of the invention.

Polyisocyanates are typically prepared by phosgenation of polyamineprecursors. For instance, polyphenyl polymethylene polyisocyanate isprepared by phosgenation of a aniline/formaldehyde condensation product.Crude polyisocyanates are also suitable for use in the practice of theinvention. Such crude isocyanates include crude toluene diisocyanatesobtained by phosgenation of a mixture of toluene diamines or crudediphenylmethylene diisocyanate obtained by phosgenation of crudediphenylmethylenediamine. Crude isocyanates are disclosed in U.S. Pat.No. 3,215,652.

Diisocyanates useful in the practice of the invention are, optionally,derivatized to form prepolymers or quasi prepolymers. In general, amodified polyisocyanate useful in the practice of the invention has afree isocyanate content of from about 1 to about 40 percent by weight.To form prepolymers, diisocyanate starting components are reacted withless than a stoichiometric amount of at least one polyfunctional activehydrogen-containing component. Suitable active hydrogen-containingcomponents include such as dipropylene glycol, propylene glycol, hydroxyesters, amines, amino alcohols, thiols, thioesters, polypropyleneglycols and the like.

One or more catalysts are beneficially used in making polyurethanes.Suitable catalysts include tertiary amines, such as, triethylenediamine,N-methyl morpholine, N-ethyl morpholine, diethyl ethanolamine, N-cocomorpholine, 1-methyl-4-dimethylaminoethyl piperazine,3-ethoxy-N-dimethylpropylamine, N,N-dimethyl-N',N'-methyl isopropylpropylene diamine, N,N-diethyl-3-diethylaminopropylamine, dimethylbenzylamine, triethylamine, tributylamine,bis(N,N-diethylamino-ethyl)adipate, 2-methylimidazole,1,4-diaza-bicyclo-(2,2,2)-octane and the like. Other suitable catalystsinclude tin compounds such as stannous chloride, tin salts of carboxylicacids such as dibutyltin di-2-ethyl hexoate, dibutyl tin dilaurate,dibutyltin diacetate, di-2-ethylhexyltin oxide, and the like, as well asother organometallic compounds such as compounds of lead, arsenic,antimony, mercury and bismuth and compounds disclosed in U.S. Pat. No.2,846,408 and the like. Silamines having carbon-silicon bonds such asthose described in German Pat. No. 1,229,290 including2,2,4-trimethyl-2-silamorpholine and the like as well as basic nitrogencompounds such as tetraalkylammonium hydroxides, alkali metal hydroxidessuch as sodium hydroxide, alkali metal phenolates such as sodiumphenolate, and alkali metal alcoholates, such as sodium methylate,hexahydro-triazines and the like are also useful catalysts. Mixtures ofcatalysts are also suitable.

Mixtures of catalysts frequently useful in forming foams from isocyanatecomponents and active hydrogen components, especially when the activehydrogen components include water. Tertiary amines are effective incatalyzing reaction between water and isocyanate groups. Transitionmetal salts and complexes are effective in catalyzing polymerization ofpolyisocyanates and other active hydrogen components, like polyols.Mixtures of such transition metal compounds as compounds of tin, ironand the like with tertiary amine catalysts are, therefore, beneficiallyused in the practice of the invention.

Metal atom-containing catalysts are generally used in a quantity of fromabout 0.0025 to 0.5 percent by weight based on active hydrogencontaining starting components. Amine catalysts are generally used in aquantity of from about 0.001 to 5 percent by weight based on activehydrogen containing starting components. Those skilled in the art areable to select a catalyst composition and quantity suitable toaccelerate the reaction between starting components. Representativecatalyst and details regarding their use are found in Kunstoff-Handbuch,Vol. VII, published by Vieweg and Hochtlen, Carl-Hanser-Verlag, Munich1966, pp. 96-102.

For production of a foam of uniform quality with good reproducabilitythe proportion of mixed starting components, catalysts, blowing agentsand other additives should be controlled as precisely as possible.However, particularly in large industrial processes, maintaining exactlyconstant amounts of catalysts is very difficult. The quality of foamproduced tends to vary because the amount of catalyst occasionally fallsoutside the narrow range of tin tolerance. Those skilled in the artrecognize tin tolerance of a formulation by shrinking or splitting infoams produced using tin compounds outside the range of concentrationstolerated. Use of the oxynitrate additives employed in the practice ofthe invention changes tin tolerance of a formulation, that is, itchanges the concentration of tin-containing compound that is suitablypresent in a formulation from which a foam which does not exhibitsubstantial shrinking or splitting can be produced. Substantialshrinking or splitting is used herein to refer to shrinking or splittingto an extent not generally acceptable for commercially produced foams.For instance, generally, shrinkage of about 50 volume percent or less asdetermined by the loss in height between the center of a foam and anedge thereof is considered commercially acceptable for flexible moldedfoams. The least shrinkage attainable is generally preferred. Generallyvisible splitting is not tolerable in commercially produced foams.

A blowing agent is generally used to generate the gas or vapor forformation of bubbles in foam formation. Any blowing agent or mixturethereof is suitable for use in the practice of the invention. Suitableblowing agents include inorganic blowing agents such as water; organicblowing agents which expand, are volatile or split off volatilecompounds at temperatures in the mold; and gases which are dissolved ormixed in the foam-forming mixture. Suitable organic blowing agentsinclude acetone; ethyl acetate; methanol; ethanol; halogen substitutedalkanes such as methylene chloride, chloroform, ethylidene chloride,vinylidene chloride, monofluorotrichloromethane, chlorodifluoromethane,dichlorodifluoromethane and the like; butane; hexane; heptane; diethylether; and the like. Gases inert to the starting components such asnitrogen, air, carbon dioxide and the like are also useful blowingagents. Compounds such as azides which decompose at temperatures presentin the mold to produce gases such as nitrogen are also useful.

The amount of blowing agent employed is not critical but should besufficient to foam the reaction mixture. Said amount will vary withfactors such as the density desired in a foamed product. Generally, fromabout 0.0005 to about 0.3 moles of gas or vapor is used for each onehundred grams of reaction mixture having an isocyanate to activehydrogen ratio of about one to one, in order to produce a foam having adensity from about 0.8 to about 5 pound per cubic foot (from about 12.8to about 80.1 kilograms per cubic meter).

Water is a particularly useful blowing agent for use in the practice ofthe invention. It costs little and adds stability to foaming. Inaddition to generating gas for foaming, water reacts quickly withpolyisocyanate components to form polyurea chains, thus contributing toearly polymer strength needed for gas retention. Generally, when wateris used, it is present in proportions of from about 1.5 to about 8weight percent of water based on total weight of active hydrogencomponents. Blowing agents which do not react with isocyanate can beused with water. The oxynitrate additives used in the practice of theinvention are conveniently mixed with the water used as blowing agent ina polyurethane formulation.

Additives such as surface active agents, antistatic agents,plasticizers, fillers, flame retardants, pigments, stabilizers such asantioxidants, fungistatic and bacteriostatic substances and the like areoptionally used in polyurethanes.

In producing polyurethane foams by the process of the invention, it isgenerally advantageous use a foam stabilizer, catalyst and blowing agentin balanced proportions to obtain a foam of a preselected cell size,structure and density. Suitable foam stabilizers are generally wettingagents or surface active agents. Nonionic surfactants and wetting agentsare generally preferred. Suitable foam stabilizers include hydrophilic,and advantageously water soluble, organo-silicon compounds, such asthose having a polydimethylsiloxane group attached to a copolymer ofethylene oxide and propylene oxide and the like. Exemplary foamstabilizing compounds are disclosed in U.S. Pat. No. 2,764,565.Organo-silicon foam stabilizers are well known to those skilled in theart. Other surface active compounds are also suitable for use inpolyurethane foams. Such foam stabilizers, cell regulating additives,surface active compounds and proprietary combinations thereof aregenerally commercially available with specific instructions as to theiruse. These compounds include paraffins, fatty alcohols,dimethylpolysiloxanes and the like.

Several characteristics of flexible foams indicate aspects of theirformation and properties. Cream time, rise time and blow off areroutinely measured during foam production. Cream time is the time fromintroduction of polyisocyanate components into active hydrogencomponents until a foaming mass changes from clear to opaque. Rise timeis the time from introduction of polyisocyanate components into activehydrogen components until a foam completes its rising, that is, untilthe foam reaches its greatest volume. A free rise foam generallycompletes its rising at blow off, which is when carbon dioxide (andother gases, if a blowing agent is used) are released. Occurrence ofblow off generally indicates that a balanced foam formulation has beenused.

Air flow is another important physical property of a foam. Air flow is ameasure of the air which will pass through a foam. It is measuredaccording to ASTM D-3574-86 (test G) in cubic feet per minute (cfm) (1cfm is about 0.47193 liters per second (l/sec)). A desired air flow fora free rise, flexible foam is generally in the range of from about 2 cfmto about 7 cfm (about 0.9 to 3.3 l/sec). Molded foams have air flows offrom about 0.1 to about 7 cfm (0.05 l/sec to about 3.3 l/sec).

Density and indention force deflection are additional important physicalproperties of foams. A typical flexible foam has a density ranging fromabout 0.8 to about 32 pounds per cubic foot (pcf), preferably from about0.8 to about 8 pcf, more preferably from about 0.8 to about 5 pcf (about13 to 80 g/l). Indention force deflection, abbreviated IFD herein, is ameasure of a foam's hardness. It is measured in pounds (lb.) accordingto the procedure of ASTM D-3574-86. A higher IFD indicates a firmer foamthan a foam having a lower IFD. Foams having different IFD values areused in different applications.

The following examples are offered only for purposes of illustrating theprocess and composition of the invention and are not to be viewed aslimiting the present invention. All parts and percentages are on aweight basis unless otherwise indicated. Zirconium oxynitrate is assumedto be without water of hydration for all calculations unless statedotherwise. Examples of the invention are designated numerically, withthe abbreviation "EX." being used in the tables for examples.Comparative samples are not examples of the invention and are designatedwith alphabetic characters and are indicated by the abbreviation "C.S."in the tables.

Examples 1 and 2 and Comparative Sample A: FORMATION OF CUP FOAMS

A cloudy admixture of 0.5 g zirconium oxynitrate (predominatelyhexahydrate) and 100 g. of a nominal polyether triol which is about 87%propylene oxide and 13% ethylene oxide polyol having a molecular weightof about 3000-4000 (referred to hereinafter as Polyol 1) is formed. Theadmixture is observed to have particles of solid in the bottom. Theadmixture is heated to about 80° C. for a period of 2 hours during whichstirring is maintained by use of a magnetic stirrer. Particles are stillvisible.

The admixture is then filtered while warm through a coarse glass fritfilter having openings measuring about 40 to about 60 microns,commercially available from Fisher Scientific Company. A solution isobtained as a filtrate. The solution is referred to hereinafter asSolution A.

The solution is analyzed by emission spectroscopy and found to have 210ppmw zirconium which would correspond to 532 ppmw zirconium oxynitratewith no molecules of water and hydration per molecule of zirconiumoxynitrate.

Flexible foams are produced on a small scale from the formulations inTable I by a cup foam procedure which approximates conditions found inproduction of slab stock foams because containers used as cups are openrather than closed (as a mold would be). A masterbatch is formed fromthe water, silicone and amine catalyst as indicated in Table I. Thesilicone compound is a polysiloxane polyalkylene oxide block copolymeravailable from Goldschmidt AG under the trade designation Tegostab®BF-2370. The amine catalyst is a mixture of 70% by weightbis(dimethylaminoethyl)ether and 30% by weight dipropylene glycol,commercially available from Union Carbide, Corp. under the tradedesignation NIAX® A-1. The masterbatch is mechanically shaken for 10minutes. Meanwhile, samples of the indicated amounts of low aciditytoluene diisocyanate (TDI) having an isomeric weight ratio of about 80toluene 2,4 diisocyanate to about 20 toluene 2,6 diisocyanate,commercially available from Dow Chemical Company under the tradedesignation Voranate® T-80, is measured into separate 100 cubiccentimeter (cc) beakers and set aside. Samples of the indicated amountsof Polyol 1 are measured into separate one quart (0.946 liter) sizepaper cups. The indicated amounts of Solution A are added to the polyolsamples to make a total of 100 grams of polyol in each cup.

Masterbatch equivalent to the amounts of each ingredient thereof listedin Table I, that is, 4.5 grams of masterbatch, is added to each polyolsample and stirred for 15 seconds using a small electric mixer. Astopwatch is started when mixing begins. Stirring is stopped foraddition of the indicated amount of stannous octoate catalyst. Mixing isresumed for 5 seconds. When the stopwatch reaches 25 seconds, theindicated amounts of diisocyanate are added quickly to form mixtureswhich are stirred 5 seconds, after which stirring is stopped. Eachmixture is then poured into an 80 ounce (oz) (2.4 liters (l)) carton andallowed to form a foam. The foam is cured in air at room temperatureovernight. The carton is then torn off the foam. A sample measuring2"×2"×1" (high) (5 cm×5 cm×2.5 cm) is cut from the foam using a bandsaw.

Air flow of each sample is measured by the procedure of ASTM D-3574-86(Test G), using an air flow meter produced by Amscor, Inc. Density isdetermined by weighing each sample of foam and dividing the weight bythe volume of the sample.

                  TABLE I                                                         ______________________________________                                        COMPONENT      C.S. A     EX. 1   Ex. 2                                       ______________________________________                                        POLYOL 1       100        85      75                                          INDEX          108        108     108                                         ISOCYANATE     46.7       46.7    46.7                                        WATER          3.6        3.6     3.6                                         SILICONE       0.8        0.8     0.8                                         AMINE CATALYST 0.10       0.10    0.10                                        TIN CATALYST   0.325      0.325   0.325                                       ZR. SOLUTION* A                                                                              0          15      25                                          RISE (sec.)    87         114     136                                         AIR FLOW cc/min.                                                                             0.32       2.2     5.9                                         DENSITY (lb./ft..sup.3)                                                                      1.5        1.5     1.4                                         ______________________________________                                         *ZR SOLUTION is a solution of 532 ppm zirconium oxynitrate in the polyol.

The data in Table I shows a substantial increase in air flow is obtainedusing about 80 and 133 ppm by weight based total active hydrogencomponents of zirconium oxynitrate.

EXAMPLES 3-5 AND COMPARATIVE SAMPLES B-D: PREPARATION OF CUP FOAMS

The procedure of Example 1 is repeated for Examples 3-5 and comparativesamples B-D, except that for Examples 3 and 4 and Samples B and C, a 20ppm solution of zirconium oxynitrate in the polyol is prepared as inExample 1 and also filtered through a medium glass frit filter (havingopenings of about 10 to about 15 microns); and no masterbatch is formed.Instead, water, silicone, tin catalyst and amine catalyst are measuredindividually for each sample. For Comparative Sample D, no masterbatchis used, and a 2 percent by weight solution of zirconium oxynitratehexahydrate in water is prepared by the procedure of Example 1 exceptthat the admixture is heated to 50° C., and is not filtered because itis a clear solution.

Foam formulations having the amounts of the ingredients indicated inTable II are produced and allowed to foam as in Example 1. Rise densityand air flow measurements made as in Example 1 are shown in Table II.

                  TABLE II                                                        ______________________________________                                        COMPO-                                                                        NENT     C.S. B  EX. 3   Ex. 4 Ex. 5 C.S. C.                                                                             C.S. D                             ______________________________________                                        POLYOL   100     75      50    25    0     100                                INDEX    108     108     108   108   108   108                                ISOCY-   46.7    46.7    46.7  46.7  46.7  46.7                               ANATE                                                                         WATER    3.6     3.6     3.6   3.6   3.6   0                                  SILICONE 0.8     0.8     0.8   0.8   0.8   0.8                                AMINE    0.10    0.10    0.10  0.10  0.10  0.10                               CATALYST                                                                      TIN      0.325   0.325   0.325 0.325 0.325 0.325                              CATALYST                                                                      ZR.      0       25*     50*   75*   100*  3.6**                              SOLUTION                                                                      RISE     81      87      93    115   --    98                                 AIR FLOW 0.61    2.3     5.4   5.6   split 0.54                               cfm                                                                           DENSITY  1.52    1.52    1.43  1.62  --    1.43                               lb/ft.sup.3                                                                   ______________________________________                                         *ZR SOLUTION is a solution calculated to have 20 ppm anhydrous zirconium      oxynitrate in the polyol.                                                     **ZR SOLUTION is a solution of 2 percent by weight zirconium oxynitrate       hexahydrate in water.                                                    

Examples 1 through 5 show that foams having properties withincommercially acceptable ranges can be made by addition of zirconiumoxynitrate to urethane-forming compositions. The data in Table II showsthat air flow measurements of foams having zirconium oxynitrateincorporated therein as a solution in a polyol are generally greaterthan that of similar foams made without the zirconium oxynitrate.Comparative Sample C shows that splitting may occur when a highconcentration of zirconium oxynitrate is used. Comparative Sample Dshows that use of a zirconium oxynitrate solution in water in this freerise foam formulation produces a foam having characteristics similar tothose of a foam having no zirconium oxynitrate.

EXAMPLES 6-9 AND COMPARATIVE SAMPLE E: PREPARATION OF CUP FOAMS HAVINGDIFFERING SOLUTIONS OF ZIRCONIUM SALTS

The procedure of Example 1 is repeated using a masterbatch and theamounts of intregients specified in Table III. For each example, 25grams of a zirconium salt solution (designated Solutions I-IV in TableIII) are used. The solutions are prepared as follows:

SOLUTION I

A mixture containing 0.5 weight percent zirconium oxynitrate hexahydratein the polyol of Example I is prepared by mixing 1 g. zirconiumoxynitrate hexahydrate and 199 g. of the polyol. The mixture is heatedfor 3 hours at 50°, then 30 minutes at 75° C. with stirring. The mixtureis then filtered through a coarse fritted glass filter funnel whilestill warm. A coarse filter is one which allows passage of particlesless than 60 μm in size (and dissolved compounds). The resultingsolution is somewhat cloudy. The filtered solution is analyzed byemission spectroscopy and found to have a zirconium concentration of 210ppm by weight. Such a zirconium concentration would correspond to aconcentration of 532 ppm by weight anhydrous zirconium oxynitrate in thepolyol.

SOLUTION II

A 50 g. sample of the mixture of zirconium oxynitrate and polyolprepared for Solution I is filtered through a medium fritted glassfilter funnel, that is one allowing passage of particles havingdiameters less than about 15 microns. The resulting solution issubstantially clear and is orange in color. The filtered solution isanalyzed by emission spectroscopy and found to have a zirconiumconcentration of 6 ppm, corresponding to a concentration of 15.2 ppm byweight of anhydrous zirconium oxynitrate in the polyol. The solution isstored for seven days at room temperature before use in forming foams.

SOLUTION III

A 50 g. sample of Solution I is filtered through a fine fritted glassfilter funnel which allows passage of particles having diameters lessthan about 5.5 microns. The resulting solution is substantially clear.The filtered solution is analyzed by emission spectroscopy and found tohave a concentration of 5 ppmw zirconium, corresponding to aconcentration of 12.7 ppm by weight of anhydrous zirconium oxynitrate inthe polyol.

SOLUTION IV

A mixture of 1 g. zirconium oxynitrate hexahydrate and 199 g. of polyolis formed and heated first 3 hours at 50° C., then 30 minutes at 75° C.with stirring. The mixture is filtered through a medium fritted glassfilter funnel to obtain a redish filtrate solution. The filtratesolution is analyzed by emission spectroscopy and found to have a 5.9concentration of zirconium, corresponding to a concentration of 15.0 ppmby weight of anhydrous zirconium oxynitrate in the polyol. The solutionis used within 3 days of preparation.

Table III lists the components of polyurethane foam-forming formulationsused in Examples 6-9 and Comparative Sample E. The air flow, density andrise time of each foam are also shown in Table III.

                  TABLE III                                                       ______________________________________                                        COMPONENT C.S.E   EX. 6   EX. 7  EX. 8  EX. 9                                 ______________________________________                                        POLYOL    100     75      75     75     75                                    INDEX     108     108     108    108    108                                   ISOCYANATE                                                                              46.8    46.8    46.8   46.8   46.8                                  WATER     3.6     3.6     3.6    3.6    3.6                                   SILICONE  0.8     0.8     0.8    0.8    0.8                                   AMINE     0.10    0.10    0.10   0.10   0.10                                  CATALYST                                                                      TIN CATALYST                                                                            0.325   0.325   0.325  0.325  0.325                                 ZR. SOLUTION                                                                            0       25 of I 25 of II                                                                             25 of III                                                                            25 of IV                              RISE(sec.)                                                                              80      111     96     93     127                                   AIR FLOW  0       3.5     4.7    4.2    5.7                                   (cfm)                                                                         DENSITY   0.026   0.029   0.027  0.027  0.027                                 g/cm.sup.2                                                                    ______________________________________                                    

The data in Table III shows that use of zirconium oxynitrate solutionsin foam forming formulations results in foams having increased air flowcompared to a foam (C.S.E) not having zirconium oxynitrate. Foams havingincorporated therein polyol solutions of zirconium oxynitrate which arefiltered through a fine or medium glass frit filter, that is Examples9-11, have somewhat larger air flows than has a similar foam (Example 8)having incorporated therein such a solution which is coarsely filtered.

EXAMPLE 10 AND COMPARATIVE SAMPLES F-H: PREPARATION OF MOLDED FOAMSUSING ZIRCONIUM OXYNITRATE SOLUTIONS IN POLYOL

The following procedure for making molded foams is followed for theformulations shown in Table IV and designated Comparative Samples F-Hand Example 10, respectively:

A masterbatch is formed of copolymer polyol (designated as Polyol A andformed from styrene, acrylonitrile, isocyanoethyl methacrylate and apolyol having an average molecular weight of about 4750 and formed froma mixture propylene oxide and ethylene oxide in a polyoxypropylene etherpolyol having an average molecular weight of about 4080, the polyolbeing end-capped with ethylene oxide to make a polyol having an averagemolecular weight of about 4850); water; diethanolamine (DEOA) and aminecatalysts. The amine catalysts are a 70% solution ofbis(dimethyl-aminoethyl ether) in dipropylene glycol, commerciallyavailable from Union Carbide Corporation under the trade designationNIAX® A-1; a 33% solution of triethylene diamine in dipropylene glycol,commercially available from Air Products and Chemicals under the tradedesignation Dabco® 33-LV; and pentamethyl, dipropylene triamine. Themasterbatch contains sufficient amounts of each of the ingredients forfive samples having the quantities designated in Table IV. Themasterbatch is mixed for about 5 minutes on a small electric mixer.

A mixture is formed of 18.7 g. zirconium oxynitrate hexahydrate and3740.5 g. of a glycerine-initiated ethylene oxide/propylene oxide polyolhaving a molecular weight of about 5000 (designated in Table IV asPolyol B). The mixture is heated for 2 hours at 50° C. and then for 30minutes at 75° C. with stirring by air driven stirrer. The mixture isthen filtered while warm through a coarse fritted glass filter funnel toremove solids and leaving a green filtrate. Analysis by emissionspectroscopy shows that the filtrate has a zirconium concentrationcorresponding to 1470 ppmw of anhydrous zirconium oxynitrate in thepolyol. The filtrate is cloudy and is shaken before use in each exampleor sample.

For each sample in Table IV, a 55.7 gram sample of the masterbatch ismeasured and placed in an 80 oz paper cup without stirring. To themasterbatch, are added sequentially the amounts of the followingingredients indicated in Table IV: the polyol designated Polyol B, thesolution of zirconium oxynitrate in Polyol B, a siloxane surfactantavailable from Union Carbide Corp. under the trade designation Y-10184designated as silicone compound; and a tin catalyst, dibutyl tinmercaptide, commercially available under the trade designation Fomrez®UL-1.

After the above ingredients are mixed by a small electric mixer for 15seconds, a mixture thereof with 48.2 grams of the toluene diisocyanateof Example 1 is formed. After 5 seconds of stirring with a smallelectric mixer, the mixture is poured into a mold measuring about 8 in.by 8 in. by 3 in. high (about 20.3 cm by 20.3 cm. by 7.6 cm), which isremoved from an oven maintained at 250° F. (121° C.). The mold has atemperature of 150° F. (65° C.) The top of the mold is clamped shut. Therise time indicated in Table IV is that time from the time theisocyanate is added to the mixture until foaming mass comes throughsmall holes in the top of the mold. Two minutes after addition of theisocyanate, the mold containing foam is placed back into the 250° F.(121° C.) oven for a period of four minutes. After the four minutes haveelapsed, the foam is removed and allowed to cool at room temperature.Shrinkage is then determined as a percentage of the thickness at thecenter of the foam relative to thickness at an edge thereof.

                  TABLE IV                                                        ______________________________________                                        COMPONENT    C.S. F   Ex. 10   C.S. G C.S. H                                  ______________________________________                                        POLYOL A     50       50       50     50                                      POLYOL B     50       25       0      25                                      INDEX        105      105      105    105                                     ISOCYANATE   48.2     48.2     48.2   48.2                                    WATER        3.8      3.8      3.8    3.8                                     SILICONE     1.65     1.65     1.65   1.65                                    Diethanolamine                                                                             1.7      1.7      1.7    1.7                                     AMINE CATALYST                                                                             0.435    0.435    0.435  0.435                                   mixture                                                                       TIN CATALYST 0.0042   0.0042   0.0042 0.0042                                  ZR. SOLUTION 0        25       50     25                                      in polyol B                                                                   ppm zirconium                                                                              0        367.5    735    367.5                                   oxynitrate*                                                                   RISE TIME sec.                                                                             35       40       65     very                                                                          slow                                    % SHRINKAGE  22       0        collapse                                                                             collapse                                ______________________________________                                         *PPM zirconium oxynitrate is expressed in terms of parts per million by       weight of total polyol, calculated from emission spectroscopy showing         concentration of zirconium in solution.                                  

The data in Table IV shows that in the foam-forming formulations used,an amount of zirconium oxynitrate solution corresponding to about 367.5ppmw anhydrous zirconium oxynitrate in total polyol can eliminateshrinkage (Example 10). Collapse of the foam of Comparative Sample G isbelieved to indicate a possible sensitivity of the formulation to 735ppmw of anhydrous zirconyl oxynitrate. Collapse of the foam ofComparative Sample H is unexplained but is believed to indicate that 367ppmw is approaching the upper limit of useful concentrations ofzirconium oxynitrate in this formulation.

EXAMPLES 11-14 AND COMPARATIVE SAMPLE J: FORMATION OF MOLDED FOAMS USINGZIRCONIUM OXYNITRATE IN WATER SOLUTIONS AND POLYOL SOLUTIONS

The procedure of Example 10 is repeated using the quantities indicatedin Table V and using, in Examples 11 and 12, a solution of one percentby weight zirconium oxynitrate in water instead of the solution ofzirconium oxynitrate in polyol B. The solution in water is prepared byforming an admixture of 99 g. of deionized water and 1 g. of zirconiumoxynitrate hexahydrate. The admixture is stirred by magnetic stirring at50° C. until all solids are dissolved. In Examples 13 and 14 the polyolsolution of Example 10 is used.

                                      TABLE V                                     __________________________________________________________________________    COMPONENT  C.S. J                                                                             Ex. 11                                                                              Ex. 12                                                                             Ex. 13                                                                             EX. 14                                        __________________________________________________________________________    POLYOL A   50   50    50   50   50                                            POLYOL B   50   50    50   25   35                                            INDEX      105  105   105  105  105                                           ISOCYANATE 48.1 48.1  48.1 48.1 48.1                                          WATER      3.8  0     1.8  3.8  3.8                                           SILICONE   1.65 1.65  1.65 1.65 1.65                                          Diethanolamine                                                                           1.7  1.7   1.7  1.7  1.7                                           AMINE CATALYST                                                                           0.435                                                                              0.435 0.435                                                                              0.435                                                                              0.435                                         mixture                                                                       TIN CATALYST                                                                             0.0042                                                                             0.0042                                                                              0.0042                                                                             0.0042                                                                             0.0042                                        ZR. SOLUTION                                                                             0    0     0    25   15                                            in polyol B                                                                   ZR. SOLUTION                                                                             0    3.8   2.0  0    0                                             in water                                                                      ppm zirconium                                                                            0    380   200  367.5***                                                                           220.5***                                      oxynitrate                                                                    RISE TIME sec.                                                                           39   58    45   52*  50**                                          % SHRINKAGE                                                                              18.75                                                                              4.17  12.5 4.17 10.42                                         __________________________________________________________________________     *Repetition of this sample gives a rise time of 38 sec. with no measurabl     shrinkage.                                                                    **Repetition of this sample gives the same rise time and slow curing.         ***PPM zirconium oxynitrate (anhydrous) is expressed in terms of parts pe     million by weight of total polyol, calculated from emission spectroscopy      showing concentration of zirconium in solution.                                Based on solution of zirconium oxynitrate hexahydrate.                  

The data in Table V shows that use of similar concentrations ofzirconium oxynitrate in water and polyol solutions is effective in thismolded foam formulation to substantially reduce shrinkage of the foams.

EXAMPLES 15-17 AND COMPARATIVE SAMPLES K-M: PREPARATION OF CUP FOAMSHAVING VARYING TIN CATALYST LEVELS

The procedure of Example 1 is repeated for Examples 15-17 andcomparative samples K-M, except that for Examples 15-17, a 0.35 weightpercent solution of zirconium oxynitrate hexahydrate in the polyol isprepared as in Example 1 using a coarse glass frit filter, and nomasterbatch is formed. Instead, water, silicone, and amine catalyst andtin catalyst are measured individually for each sample. The finalconcentration of zirconium oxynitrate in Examples 15-17, as calculatedfrom the zirconium detected by emission spectroscopy, is 175 ppmanhydrous zirconium oxynitrate in total polyol.

Foam formulations having the amounts of the ingredients indicated inTable VI are produced and allowed to foam as in Example 1. Rise densityand air flow measurements made as in Example 1 are shown in Table VI.

                  TABLE VI                                                        ______________________________________                                        COMPO-                                                                        NENT     C.S. K  C.S. L  C.S. M                                                                              Ex. 15                                                                              EX 16.                                                                              EX 17                              ______________________________________                                        POLYOL   100     100     100   50    50    50                                 INDEX    108     108     108   108   108   108                                ISOCY-   46.7    46.7    46.7  46.7  46.7  46.7                               ANATE                                                                         WATER    3.6     3.6     3.6   3.6   3.6   0                                  SILICONE 0.8     0.8     0.8   0.8   0.8   0.8                                AMINE    0.10    0.10    0.10  0.10  0.10  0.10                               CATALYST                                                                      TIN      0.20    0.25    0.30  0.8   0.9   1.0                                CATALYST                                                                      ZR.      0       0       0     50*   50*   50*                                SOLUTION                                                                      AIR FLOW 3.9     0.5     0.18  3.5   2.3   0.49                               cfm                                                                           ______________________________________                                         *ZR SOLUTION is a solution calculated to have 175 ppm anhydrous zirconyl      nitrate in the polyol solution.                                          

Reductions in shrinkage and accompanying raising of air flow inpolyurethane foams are generally associated with reduced tin-containingcatalyst levels. Table VI shows that in foam-forming formulationsincorporating oxynitrate salts according to the practice of theinvention, air flow is maintained without decreasing tin-containingcatalyst concentrations. For instance, Example 15 and Comparative SampleK have similar air flows, as do Example 17 and Comparative Sample L, butmore tin-containing catalyst is used in the Examples which containzirconium oxynitrate. Use of zirconium oxynitrate, thus, allows the useof greater concentrations of tin-containing catalyst than wouldotherwise be possible in the formulations without the oxynitrate salts.Oxynitrate salts used according to the practice of the invention, thus,modify the tin tolerance of such formulations. Generally, use ofoxynitrate salts according to the practice of the invention alsoenlarges the range of concentrations of tin-containing catalysts thatare suitably used in a polyurethane forming composition.

The examples of the invention show that zirconium oxynitrate in solutionin polyols or in water is useful as a cell opener and/or shrinkagelimiting agent in a variety of polyurethane foam-forming formulations.These examples are only exemplary of the wide utility of the process ofthe invention which is expected to have similar effects in anypolyurethane foam-forming formulation, including those formulationswhich also utilize other blowing agents and/or fillers, as well asformulations including different active hydrogen compounds, differentisocyanates, different catalysts and different additives, such asdifferent silicone compounds.

We claim:
 1. A composition comprising a mixture of a polyether polyol,at least one oxynitrate salt of a metal of Group IV B of the Mendeleefperiodic table and at least one polyisocyanate component.
 2. Thecomposition of claim 1 wherein the salt is zirconium oxynitrate.
 3. Thecomposition of claim 1 wherein the salt is present in a concentration ofat least about 3 ppm by weight.
 4. The composition of claim 3 wherein atleast part of the oxynitrate salt is dissolved in the polyol.
 5. Thecomposition of claim 4 wherein the oxynitrate salt is also present inthe form of particles having diameters of less than about 60 microns. 6.The composition of claim 1 wherein the oxynitrate salt is dissolved inthe polyol or present in the form of particles having diameters of lessthan about 60 microns.
 7. The composition of claim 6 wherein theparticles have diameters of less than about 15 microns.